In cross-country skiing, the skis are subject to two distinct actions, a kick action and a glide action. To better understand how these actions are implemented, one must understand the basic structure of the cross-country ski. Cross-country skis have an arched bottom surface with a central gripping portion that is textured or otherwise treated to grip the snow surface when brought into contact with the snow. The arch or camber of each ski is designed to maintain the gripping portion of the bottom surface above the snow surface during the glide action, where the weight of the user is well distributed between both skis and the skis are simply supporting the user on the snow surface. When the gripping portions of the bottom surfaces of the skis are raised above the snow surface, the gripping portions do not engage the snow surface, allowing the skier to glide on the surface of the snow. During the kick action, the user distributes his/her weight such that it is primarily on one ski (a first ski) which provides an additional downwards load or force on the first ski. This increased force reduces the camber and brings the gripping portion into contact with the snow surface. When the gripping portion of the first ski, bearing a substantial portion of the weight of the user, is engaged with the snow surface, the user moves his/her body relative to the first ski to impart forward motion of a second ski across the snow.
Thus, the kick action empowers the user to impart forward propulsion and the glide action controls the distance traversed by the user in response to the kick action. Classically, the selection of cross-country skis has considered both actions important in the selection of skis for a user. Accordingly, the selection process has attempted to match the height and weight of the user with the length and stiffness of the skis, as has been done with down hill ski selection.
One method of refining the ski selection after the preliminary selection has been made based generally on the height and weight of the user is to conduct a paper test. In this test, the intended user stands on the skis with a piece of paper held under the gripping portion. If the paper can be removed, then the user can be sure that the gripping portion is raised. While this test has been used, it is most easily conducted and usually provides more reproducible results when the paper is manipulated by a fitter rather than by the user, and thus cannot be effectively performed by the user alone. Furthermore, this test does not provide an indication of whether the user will be able to deflect the skis sufficiently during the kick portion of the skiing action. For more experienced skiers or with the assistance of a ski fitter, it may be possible for the skier to simulate the user's kick action by the appropriate shifting of his/her weight while a ski fitter tries to remove the paper during this simulated kick action. However, this requires experience on the part of the skier and a ski fitter to assist.
U.S. Pat. No. 3,922,908 teaches a device which helps to better quantify the characteristics of skis without requiring the skis to be fitted directly to the skier. The device does so by applying a load to a ski and measuring the resulting pressure distribution along a baseplate on which the ski rests. By matching the load applied to the ski to the loads which would be applied by the intended user during the kick action and the glide action, the resulting performance characteristic of the ski can be predicted. The testing device is complex and provides a recording curve which requires some degree of technical expertise to interpret, as well as requiring knowledge of or accurate estimation of the forces imparted by the intended skier. These requirements would appear to severely limit the practical applications of the device.
The problem of determining the appropriate ski loads or forces generated by a skier has been addressed by U.S. Pat. No. 4,164,875, which teaches a ski testing device that includes a scale for weighing the intended user. This device can measure the load required to obtain a certain degree of flatness in the ski being tested, or can measure the degree of deflection of the ski which results from applying a certain load. While this device does have the capacity to weigh the skier, it still requires the qualification of individual skis to the person weighed. While this device appears to have more practical use than that of the '908 patent, it is still limited in that it is complex and requires a trained operator. Furthermore, the patent also teaches the importance of considering both the height and the weight of the skier when making a ski selection. Here again the skis to be tested for suitability are preselected for the user based on matching the ski length to the height and weight of the user, and then tested based on the weight of the user.
A severe limitation of the above referenced techniques is that they do not guide a user in selecting a particular pair of skis, but rather require expert assistance and rely on a trial-and-error approach to determine whether a particular ski or pair of skis is suitable for a user. This trial-and-error approach, in addition to being extremely time consuming, may also be frustrating for users, particularly those who are inexperienced.
The importance of weight as a significant factor in the selection of appropriate skis has been appreciated by the racing community, and some racing skis now have imprinted thereon, in addition to the ski length, suggested weight ranges to help remind the racer that this factor should be considered in addition to stiffness when selecting a ski. It should be apparent from ordering practices that weight, although significant, is not the controlling factor in selecting skis. Racing skis are currently ordered based on length, weight and stiffness. A skier having a weight in a particular range may have three different ski lengths recommended, each length corresponding to a particular relative degree of stiffness. While such markings have been useful for skiers having sufficient experience to judge what relative degree of stiffness they desire, such markings have not been employed for skis intended for less experienced users, who lack the experience to properly select a particular degree of stiffness. Furthermore, even the expert racer may wish to refine the selection process with the paper test discussed above.
A further limitation of such suggested weight ranges is that many users, and frequently users who are not particularly athletic, are reluctant to reveal their weight in a setting such as a retail store or a rental agency. The hesitancy of many users to disclose their correct weight is frequently so great that, if requested to publicly disclose their weight, some users may either decide not to proceed with selecting skis or, alternatively, may misrepresent their weight by underestimating it. In the latter case, the user may underestimate his or her weight to an extent that the user selects skis which will not properly function in the glide mode when the actual weight of the user is minimized on the individual skis by distributing the weight equally between the skis. For example, if a user having an actual weight of 150 lbs. (68 kg) selects skis based on a misrepresented weight of 100 lbs. (45 kg), each of the skis so selected is designed to glide, properly under a load of 50 lbs. (23 kg). The 150 lbs. (68 kg) user cannot apply only 50 lbs. (23 kg) to each ski, and thus will not experience proper performance in the glide mode.
Similarly, the staff in stores or rental agencies may be reluctant to ask for the weight of a user. More experienced staff frequently estimate the height and weight of a user visually in order to select skis to avoid asking the user. This approach requires considerable experience to employ effectively, and even then is of questionable accuracy.
Thus, there is a need for a simple system and method for allowing users, particularly inexperienced users, to readily select appropriate skis to suit the weight of the user. There is also a need for a system and method for allowing users to select appropriate skis without having the weight of the user revealed.